This walkway is so narrow it needs its own light to stop pedestrian traffic jams.

Underneath the city that invented pilsners are a series of historic tunnels that have been storing beer for centuries.

You can row a boat through this ancient underground reservoir.

Floating swimming pool within a moored vessel.

Architectural monsters are devouring this palace's every door and window.

This hidden Art Nouveau courtyard is an opulent feast for the eyes.

2300-year-old Roman road connecting the empire.

The yawning maw of this pagan visage is said to bite off the hands of liars.

The "Paris of the Prairies" wouldn't be complete without a replica of the iconic landmark.

A windswept necropolis carved into the rocks overlooks the "most Portuguese town in Portugal."

Houses are tucked between, on, and underneath giant boulders.